Due to the confined space of an aircraft fuselage interior, treatment fluids (e.g., an organic corrosion inhibitor compound) have traditionally been applied by a spray gun system manually manipulated by a technician so as to direct a spray of fluid onto the aluminum surfaces of the aircraft fuselage interior. Specifically, during aircraft manufacturing, a technician must physically enter the aircraft fuselage once the fuselage junction has been completed in order to mask, and thereby protect, certain areas of the aircraft interior that cannot be contaminated with the corrosion inhibitor compound. Once the interior fuselage surfaces have been masked, the machine spray guns are then prepared with the corrosion inhibitor compound to be applied. Numerous (typically between ten to twelve) technicians must then enter the interior of the fuselage in order to begin applying the corrosion inhibitor compound. It is important to emphasize that at this stage of the manufacturing process, there is no installed floor and thus the risk to technician safety is very high. In addition, this safety risk progressively gets worse during application of the corrosion inhibitor compound due to the overspray created by the spray guns which in turn blocks the technician's view on the confined space. Furthermore, after one hour of application, the technician must take certain precautionary breaks in order to shower because of the heat that is typically experienced within the fuselage interior during the spraying procedure, especially in the summer time when ambient temperatures can reach approximately 40° C. This lack of visibility within the confined space of the fuselage interior during spray application of the corrosion inhibitor compound may therefore cause the following issues:                (a) Product puddling—Excess corrosion inhibitor compound may accumulate (puddle) due to the excess applied compound flowing or leaking into certain areas.        (b) Inadequate product application—The technician may not be able to visually determine in some areas of the fuselage interior whether the proper amount of corrosion inhibitor compound has been applied due to the lack of visibility and the overspray.        (c) Bare surfaces—Some areas within the fuselage interior are so confined as to prevent access by the spray gun thereby resulting in no corrosion inhibitor compound being applied.        (d) Excess product application—Due to low visibility conditions, the technician may apply more than the specified amount of the corrosion inhibitor compound thereby increasing the coating thickness above normal which in turn increases aircraft weight.        
The manual process to apply the organic corrosion inhibitor compound on the interior surfaces of an aircraft fuselage as discussed above needs to follow strictly the requirements of the product. For this reason, there are many issues that arise by the manual application process, such as longer cycle times for each process step that results in low productivity, additional time to rework, increased labor costs, lower quality of the processes and less reliability on the results. These disadvantages are the result of the current craft process for application of the fluid products. The sub-processes demand high man-hours since each skilled technician is responsible for many tasks. Hence, the current manual application processes lack repeatability and standardization while also requiring a very slow learning curve for the technician.
Besides the environmental savings and ergonomic issues, an automated process also improves the quality of product application since the interior fuselage surfaces are more adequately covered. As such, the different automated processes are more reliably repeatable thereby in turn resulting in beneficially reducing aircraft weight.
One prior proposal for identifying surface locations within the interior of an aircraft fuselage by a video camera mounted on a robot end effector of a mobile assembly is disclosed in U.S. Pat. No. 8,941,817 (the entire content of which is expressly incorporated hereinto by reference). The disclosed mobile assembly is capable of moving onto flat surfaces inside the fuselage with the main function of the video camera and its associated system being to identify interior fuselage structures for future bracket installation. No disclosure is apparent whereby the mobile assembly may automatically move into and out of the aircraft fuselage interior or the application of a treatment fluid within the aircraft fuselage interior.
Thus, although individual automated techniques may exist, there still exists a need in this art for a fully automated systems and methods by which the interior of an aircraft fuselage may be coated with an applied treatment fluid (e.g., a corrosion inhibitor compound). It is towards fulfilling such needs that the embodiments disclosed herein are directed.